1. Field of the Invention
The present invention relates to an LED lighting module and a method of making an LED lighting module.
2. Description of the Related Art
FIG. 24 shows an example of conventional LED lighting module. The LED lighting module 900 shown in the figure includes a substrate 91, an LED chip 95, a sub-mount substrate 96, a case 97 and a sealing resin 99. The LED lighting module 900 may be used in various applications, such as a point light source of an electronic device when structured as a relatively small module, an elongated bar-like light source when provided with a plurality of LED chips 95 arranged on an elongated substrate 91, and a surface light source when provided with a plurality of LED chips 95 arranged in a matrix on a substrate 91.
The substrate 91 is made up of a base 92, an insulating layer 93 and a wiring layer 94. The base 92 is a metal plate made of e.g. aluminum. The insulating layer 93 is made of e.g. an insulating resin and covers the upper surface of the base 92 in the figure. The wiring layer 94 is provided on the insulating layer 93 and constitutes an electrical connection path to the LED chip 95. The LED chip 95 is made up of a plurality of semiconductor layers formed one on top of another, and mounted on the sub-mount substrate 96. The LED chip 95 and the wiring layer 94 are connected to each other via a wire. The sub-mount substrate 96 is made of e.g. Si and bonded to the insulating layer 93. The case 97 surrounds the LED chip 95 and has a reflective surface 98. The sealing resin 99 covers the LED chip 95.
To enhance the brightness of the LED lighting module 900, effective heat dissipation from the LED chip 95 to the base 92 needs to be realized. However, the insulating layer 93 is disposed between the LED chip 95 and the base 92. The insulating layer 93, which needs to have insulating properties, generally has a lower thermal conductivity than e.g. metal. Thus, heat dissipation from the LED chip 95 has been insufficient.